A worm gear mechanism is installed, for example, in a power steering device of a vehicle (see, for example, FIG. 14 in Patent Literature 1).
The worm gear mechanism as disclosed in Patent Literature 1 is provided with a worm coupled to an electric motor through a worm shaft, and a worm wheel configured to mesh with the worm. It is a transmission mechanism configured to boost and transmit auxiliary torque generated by the electric motor from the worm to the worm wheel.
In general, when the worm is rotated and force is applied in a direction of pushing the worm wheel, the worm receives reaction force from the worm wheel at a contact point of the worm and the worm wheel. It is preferred that strength of the worm gear mechanism be enhanced as it may contribute to extending a life of the worm gear mechanism.